Recording and projecting sound on film apparatus



April 30', 1935.. R. EVANS 1,999,754 l RECORDING' ND PROJE'GTING SOUND0N1 FILM 'PARATUS Filed April 22,. 1932 A lm/EMDR.

Plantea Apr. 30.1935 1,999,754

UNITED STATES PATENT lOFFICE RECORDING -AND PROJECTING SOUND 0N FILMAPPARATUS Raymond Evans, Washington, D. C., assigner tol l Arthur M.Hyde, as Secretary of Agriculture of the United States ofAmericalApplication April 22, 1932, Serial No. 606,900

4 Claims. (Cl. 274-11) (Granted under the act of March 3, 1883, asamended April 30, 1928; 370 0. G. 757) 'I'he invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes without the payment ofkany royalty thereon.

'Ijhis inventionrelates to the art of mechanically recording sound onmotion picture film, and has for its primary object the development of asystem of sound recording and reproduction combining the advantage ofautomatic synchronismk of sound and picture, inherent in thephotographic effective a simple and easily-operated sound-film systemrequiring simple and inexpensive mechanism for the reproduction ofsound, applicable either to 35 or 16 millimeter nlm, and well-adaptedfor the economical presentation of talking pictures with portableequipment in the school, the home, or elsewhere, by non-professionaloperators.

A further object of the invention is to provide a sound-film systemembodying a mechanical sound-track relatively free from danger of injuryfrom ordinary sources of abrasion and from deposits of dust or oil, thatare common sources of damage and of consequent distortion of sound inthe use of sound-film with photographic soundtrack.

A further object of the invention is provide a method of impressing onmotion picture film a mechanical sound-track that does not partiallysever a strip from the border of the film, yet at the same time isrecessed when the film' is normally rolled, so as to protect itfrominjury.

A further object of the invention isto make effective. a sound-filmsystem embodying'the use of a simple pick-up such as is used in theseparate disk and film systemyet obviating en-v y simple pick-up unitand associated amplifier and speaker, similar in operation to theuniversally familiar phonograph pick-up.

Figure 1 is a diagrammatic outline of the essentials of the recordingunit hereinafter described.

Figure 2 is a supplementary view of the recordsimilar Aparts flanged onone end and faced on the other end by av disk of fibre or other similartough material 3 suitable to serve as an anvil to support film I underthe impact of recording stylus 4. The/length of drum 2 is such thatthefilm runs witliaone edge flush with the face of fibre disk 3 when` theother edge is running against the flange. Stylus 4 is a chisel-pointedtool of lsapphire, agate or similarvery hard material, driven by thearmature of a floating recording assembly 5 responsive to a suitablesystem for amplifying the modulations of a sound current, bears againstthe exposed edge offllm I with its edge at an angle of 45 degrees, moreor less, to the exposed face of film I, and with its mounting inclinedwith reference to the direction of movement of film I in accordance withstandard phonographic construction. Thus stylus 4 rests against theexposed .corner of the exposed edge of film I. As film I is drawn overrevolving drum 2 it passes under a red-hot wire 6, or other suitableheating element, designed to render the ex'- posed edge of film Imomentarily slightly plastic,

stylus 4 on film I are balancedso as to obviate 4 distortion throughlack of contact due to jumping of recording unit 5. In other words, thestylus is damped by applying suiiicient pressure to the'cutting head toprevent the entire record- L ing assembly 5 from bouncing clear of filmI, under the thrust of the stylus. Thus stylus 4 cuts on one corner ofthe exposed edge of lm I, a sine wave corresponding to the modulationsof the sound current, full modulation lying between the vertex of theangle or corner against which stylus 4 rests and the line of maximumdepth .9-9 to which stylus 4 can drive without penetrating the emulsion8 on the opposite side of film I as illustrated by line 9 9 in Fig. 3(roughly plus or minus five mills, according to the angle at whichstylus 4 is applied to film I).

The record, or sine wave cut by stylus 4, is essentially a hill-and-dalephonographic record on the edge of film I, and reproduction is effectedby use of a suitable phonograph pick-up and associated, amplier andspeaker, the needle being a chisel-pointed sapphire or similar jewel andthe film running over a properly mounted drum or roller, similar to thatused in recording.

For this method the following advantages may be cited:

With zero modulation (silence) the corner of the edge of the film,properly smoothed by preparatory polishing l(as, for example, by shavingand burnishing) offers the contact with the recording stylus mostdesirable from the standpoint of ground-noise reduction, since suchcontact minimizes friction, an important source of objectionable noise.

With minimum modulation (as in pianissimo passages in music) the cornerof the film offers correspondingly small resistance to the impact of thestylus, thus facilitating faithful recording with low power, withconsequent relative freedom from the distortion inherent in highamplification. When the modulated current is stronger and the stylustherefore tends to cut deeper into the film, the constantly-increasingcross section of the medium offers resistance that provides a dampingeffect desirable where a floating cutting head is used, as in thisinstance.

As compared with other possible positions for a mechanical sound trackon film, the position here advocated has the following advantages:

The use of the edge of the film and a chiselpointed stylus obviatesentirely the danger of the stylus "jumping the track, inherent in bothlateral-cut and hill-and-dale recording in a groove.

Edge-recording obviates the danger of cutting entirely through the filmand thus shearing a strip from the border thereof,l a danger inherent inany method involving the cutting of a groove sound-track on the borderof the film between the edge and the sprocket holes, or elsewhere.

Edge-recording at an angle as specified permits the use of a positiveanvil to support the film under the impact of the stylus, thus obviatingthe danger of distortion owing to buckling, difficult to avoid if thestylus drives with its edge parallel that of the film. y

Edge-recording at an angle as specified permits full modulation in thesmooth and dense cellulose base without allowing the stylus to penetrateto the tough and granular emulsion, which is not a suitable medium foruse in recording.

Edge-recording at an angle as specified puts the sound track in asheltered position, so that it is largely protected from accidentalinjury when the film is rolled normally, since the projecting emulsion,and more or less of the base it adheres to, serve as a guard, the trackitself being recessed. With reference to the complete system, coverinboth recording and reproduction, and involving, not only the featuresfor which originality is claimed, but also several basic steps inmechanical recording and reproduction commonly known to the art, thefollowing advantages are evident:

It combines automatic synchronism of sound and picture with thesimplicity and certainty oi response of the disk talking-picture system.

of sound and picture with relative freedom from injury to sound trackfrom ordinary sources of abrasion and from deposits of dust or oil,common and serious sources of injury to the photographic sound track.

Because of the hardness of the medium in which the sound track is cut,the record may be played much more often without serious loss of qualityin reproduction than either the standard disk or the photographicrecord.

To those skilled in the art it will be apparent that this system may bemodifled in detail and still accomplish the desired end, withoutdeparting from the spirit of my invention.

Having thus described my invention and the method of using it, I claimas new and useful and my own invention the following, for which I desireto secure Letters Patent:

1. A machine for making sound records on the corner of a film, means forfeeding said film past a conventional recording mechanism activating achisel-pointed stylus, substantially as described, said stylus disposedto the plane' of the film surface in a plane at a transverse angle ofincidence of substantially 45 degrees, said stylus thereby subjected tocontinuous contact with the corner of said film, in motion, a supportfor said film against the thrust of said stylus at the area of contact.

2. A method for mechanically recording sound on motion picture fllm,which comprises contacting of a motion picture film with a recordingmechanism having a stylus connected thereto disposed to the plane ofs'aid film surface in a plane at a transverse angle of incidence ofsubstantially 45 degrees and thus continuously contacting with saidstylus said film on the corner and in such a position, and subjectingsaid lm to the action of said stylus so positioned on the corner of saidfilm.

3. A method for mechanically recording sound on motion picture lm, whichcomprises subjecting a corner of a motion picture film to the action ofa recording mechanism disposed to the plane of said film surface in aplane at a transverse angle of incidence of substantially 45 degrees.

4. A method of mechanically recording sound on motion picture film, inwhich a recording mechanism is used to drive a chisel-pointed stylus,held continuously in contact with one corner of said film, with saidstylus centered on said corner in a plane inclined at an angle ofsubstantially 45 degrees to the plane of the adjacent surface of saidlm, and pressing thus on said corner while said film is driven over ananvil member designed to support said film solidly under the thrust ofthe said stylus.

RAYMOND EVANS.

